doc: update issue template

Change-Id: Iaa23d27043e6a050075b40072e466623418ba977
Reviewed-on: https://go-review.googlesource.com/19878Reviewed-by: Rob Pike <r@golang.org>

.github/ISSUE_TEMPLATE

@@ -7,7 +7,9 @@ Please answer these questions before submitting your issue. Thanks!
 
 
 3. What did you do?
-(Use play.golang.org to provide a runnable example, if possible.)
+If possible, provide a recipe for reproducing the error.
+A complete runnable program is good.
+A link on play.golang.org is best.
 
 
 4. What did you expect to see?